Crystallographic study of hydrated polycrystalline M-(beta '',beta)-ferrites (M = K+, Mg2+, Ca2+)

A complete crystallographic study and the ionic distribution in the conduct ion layers, including H2O, of polycrystalline Cd2+-stabilised K+-beta/beta " -ferrite, and Mg2+, Ca2+ ionic exchange derivatives is presented. Both th e parent compound and the ionic exchange products are not single phases, bu t present a mixture of the beta "- and beta -phases. The weight percent of water molecules calculated from Rietveld analysis is 0.96% for K+, and 2.41 % for Mg2+ and Ca2+, in good agreement with the weight losses measured by t hermogravimetric analysis of 1.5, 2.2 and 2.5%, respectively. (C) 2000 Else vier Science BN. All rights reserved.